Present embodiments relate generally to actuation of vanes in a gas turbine engine. More specifically, present embodiments relate to, without limitation, a rotary actuator for actuation of one or more rows of guide vanes of a gas turbine engine.
In a gas turbine engine, air is pressurized in a compressor and mixed with fuel in a combustor for generating hot combustion gases which flow downstream through turbine stages. Gas turbine engines generally possess a forward end and an aft end with several core or propulsion components positioned axially there between. An air inlet or intake is located at a forward end of the engine. Moving toward the aft end, in serial flow communication, the intake is followed by a compressor, a combustion chamber, and a turbine. It will be readily apparent to those skilled in the art that additional components may also be included in the engine, such as, for example, low-pressure and high-pressure compressors, and high-pressure and low-pressure turbines. This, however, is not an exhaustive list.
The compressor and turbine generally include rows of airfoils that are stacked axially in stages. Each stage includes a row of circumferentially spaced stator vanes and a row of rotor blades which rotate about a center shaft or axis of the turbine engine. The compressor may include a series of adjustable airfoils, commonly referred to as vanes, to vary flow characteristics of the compressed air moving through the compressor blades. Similarly, the turbine may include rows of adjustable or static vanes, or a combination thereof, interspaced in the engine axial direction between rotating airfoils commonly referred to as blades.
An engine also typically has a first high pressure shaft axially disposed along a center longitudinal axis of the engine. The high pressure shaft extends between the high pressure turbine and the high pressure air compressor, such that the turbine provides a rotational input to the air compressor to drive the compressor blades. A second low pressure shaft joins the low pressure turbine and the low pressure compressor. The low pressure second shaft may also drive a fan which creates thrust for an aircraft in flight. This connection with the low pressure shaft may be direct or indirect, for example through a gearbox.
In operation, air is pressurized in a compressor and mixed with fuel in a combustor for generating hot combustion gases which flow downstream through turbine stages. A high pressure turbine first receives the hot combustion gases from the combustor. As the combustion gas flows downstream through the turbine stages, energy is extracted therefrom and the pressure of the combustion gas is reduced. The turbine stages extract energy from the combustion gases by converting the combustion gas energy to mechanical energy. In turn, the turbine provides a rotational input to the air compressor to drive the compressor blades. This powers the compressor during operation and subsequently continues driving the turbine.
In the area of the gas turbine engine, various stages of vanes are used to provide desired flow characteristics to the compressor and turbine rotor blades. Some of the vanes may be of a variable geometry, meaning they are actuatable between multiple positions to adjust airflow into the compressor and/or the turbine. For example, at start up and shortly thereafter, it may be desirable to limit airflow into the compressor so that proper amounts of airflow are present for ignition in the combustor. However, at cruise conditions, it may alternatively be desirable to increase the amount of airflow to the compressor and combustor once the engine is at higher operating temperature and is burning higher amounts of fuel. Similarly, a still further amount of airflow may be desirable at take-off.
The prior art has used linear piston actuation for adjustment of vanes. Prior art vane actuators are in many cases integrated with the fuel metering system such that accessing the actuator would first require removal of the fuel metering unit. Additionally, with a piston actuator, the extension of the piston results in exposure of the piston which must rely on a piston seal to inhibit contamination of the actuator. Further, piston actuators have been typically arranged with one single actuator for multiple stages. Therefore, independent actuation of stages is more complicated.
As may be seen by the foregoing, it would be desirable to improve these functions and structures within gas turbine engine components.
The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded subject matter by which the scope of the instant embodiments are to be bound.